J/A+A/587/A139 Water lines spectra of 4 protostellar objects (Herpin+, 2016)
Herschel-HIFI view of mid-IR quiet massive protostellar objects.
Herpin F., Chavarria L., Jacq T., Braine J., van der Tak F.,
van Dishoeck E.F., Baudry A., Bontemps S., Kristensen L., Schmalzl M.,
Mata J.
<Astron. Astrophys. 587, A139 (2016)>
=2016A&A...587A.139H 2016A&A...587A.139H (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Spectroscopy
Keywords: ISM: molecules - ISM: abundances - stars: formation -
stars: protostars - stars: early-type - line: profiles
Abstract:
We present Herschel/HIFI observations of 14 water lines in a small
sample of galactic massive protostellar objects: NGC6334I(N),
DR21(OH), IRAS16272-4837, and IRAS05358+3543. Using water as a tracer
of the structure and kinematics, we aim to individually study each of
these objects, to estimate the amount of water around them, but to
also shed light on the high-mass star formation process. We analyze
the gas dynamics from the line profiles using Herschel-HIFI
observations acquired as part of the WISH key-project of 14 far-IR
water lines (water, H217O, H218O), and several other species.
Then through modeling of the observations using the RATRAN radiative
transfer code, we estimate outflow, infall, turbulent velocities,
molecular abundances, and investigate any correlation with the
evolutionary status of each source. The four sources (plus previously
studied W43-MM1) have been ordered in terms of evolution based on
their SED:
NGC64334I(N)-W43-MM1-DR21(OH)-IRAS16272-4837-IRAS05358+3543. The
molecular line profiles exhibit a broad component coming from the
shocks along the cavity walls associated with the protostars, and an
infalling (or expansion for IRAS05358+3543) and passively heated
envelope component, with highly supersonic turbulence likely
increasing with the distance from the center. Accretion rates between
6.3x10-5 and 5.6x10-4M☉/yr are derived from the infall
observed in three of our sources. The outer water abundance is
estimated to be at the typical value of a few 10-8 while the inner
abundance varies from 1.7x10-6 to 1.4x10-4 with respect to H2
depending on the source. We confirm that regions of massive star
formation are highly turbulent and that the turbulence likely
increases in the envelope with the distance to the star. The inner
abundances are lower than the expected 10-4 perhaps because our
observed lines do not probe deep enough into the inner envelope, or
because photodissociation through protostellar UV photons is more
efficient than expected. We show that the higher the infall/expansion
velocity in the protostellar envelope, the higher is the inner
abundance, maybe indicating that larger infall/expansion velocities
generate shocks that will sputter water from the ice mantles of dust
grains in the inner region. High-velocity water must be formed in the
gas-phase from shocked material.
Description:
The figures 2-5 show water line profiles from observations with the
Herschel Space Observatory (all observational parameters can be found
in the Table 2 of the paper). The reduced data for all the observed
lines are given in the individual ASCII files, labelled as follows:
sss_nnnn.dat, where "sss" represents the observed source name and is
"i05" for IRAS05358+3543, "i16" for IRAS16272-4837, "DR" for DR21(OH),
and "N63" for NGC6334I(N), respectively; "nnnn" is the frequency (in
GHz) of the observed line transition (e.g. "1113" for "1113 GHz").
Objects:
-----------------------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------------------
20 39 01.01 +42 22 50.2 DR21OH = DR 21 (OH)
05 39 10.4 +35 45 19 IRAS05358+3543 = IRAS 05358+3543
16 30 59.2 -48 43 48 IRAS16272-4837 = IRAS 16272-4837
17 20 54 -35 45.0 NGC6334I(N) = NAME NGC 6334 I(N)
-----------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 49 57 List of spectra
sp/* . 57 Individual 1-D spectra
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Source Source name
16- 36 A21 --- Line Water line
38- 49 A12 --- FileName Name of the 1-D spectrum file in subdirectory sp
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 20 E20.10 km/s Vlsr LSR velocity
22- 34 E13.5 K Tmb Main beam temperature
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Acknowledgements:
Fabrice Herpin, herpin(at)obs.u-bordeaux1.fr
(End) Fabrice Herpin [LAB/OASU, France], Patricia Vannier [CDS] 20-Jan-2016